1. Field of the Invention
The present invention relates to a chuck device for clamping a tool.
2. Description of the Related Art
Recently, there is a strong demand of reducing weight for a chuck device. It is proposed to form a body of light alloy such as aluminum. Incidentally, the structure according to the related art is the same as that of a first embodiment of the present invention. Accordingly, the structure of the related art will be described with reference to FIGS. 1 to 4.
For example, a chuck device with a loosening preventing mechanism has been proposed in which a plurality of claws 3 inserted into a hole 2a provided at an end of a body 2 are opened, closed and slid by the rotation of a rotary sleeve 1 and a tool 4 is clamped by means of the claws 3, wherein an annular ratchet wheel 5 is provided on the body 2, an annular nut member 6 to be engaged with the claws 3 and to be rotated together with the rotary sleeve 1 is fitted in the body 2 inside of the rotary sleeve 1, a retainer spring member 7 detachably retained with a tooth of the ratchet wheel 5 is arranged outside of the ratchet wheel 5, the retainer spring member 7 is arranged to rotate around the ratchet wheel 5 in accordance with the rotation of the nut member 6, the retainer spring member 7 is mounted on the nut member 6 by convex/concave engagement means, and a retainer portion keeps a condition that the ratchet wheel 5 and the retainer spring member 7 are retained to each other and a condition that the engagement between the ratchet wheel 5 and the retainer spring member 7 is released.
In such a chuck device, if the body is made of light alloy such as aluminum, the ratchet wheel is necessarily made of light alloy.
Conventionally, if the body is made of iron, in view of rust-proof property, nickel plate is applied to the body. However, in the case where the body is made of light alloy such as aluminum, there is no problem such as rust and hence the plating process is unnecessary.
However, studying various aspects, it has been confirmed that, even if the body is made of light alloy such as aluminum, unless the plating process is performed, the ratchet teeth of the ratchet wheel are worn due to repeated and continuous engagement between the retainer spring made of steel and the ratchet teeth, so that the loosening preventing mechanism does not work, disadvantageously. Furthermore, it has been confirmed that in the case where the surface of the body is coated, a coating is applied also to the inner surface of a hole of the body whereby the excellent result is obtained.